Molecular and phylogenetic analysis of MADS-box genes of MIKC type and chromosome location of SEP-like genes in wheat (Triticum aestivum L.).

Transcription factors encoded by MIKC-type MADS-box genes control many important functions in plants, including flower development and morphogenesis. The cloning and characterization of 45 MIKC-type MADS-box full-length cDNA sequences of common wheat is reported in the present paper. Wheat EST databases were searched by known sequences of MIKC-type genes and primers were designed for cDNA cloning by RT-PCR. Full-length cDNAs were obtained by 5' and 3' RACE extension. Southern analysis showed that three copies of the MIKC sequences, corresponding to the three homoeologous genes, were present. This genome organization was further confirmed by aneuploid analysis of six SEP-like genes, each showing three copies located in different homoeologous chromosomes. Phylogenetic analysis included the wheat MIKC cDNAs into 11 of the 13 MIKC subclasses identified in plants and corresponding to most genes controlling the floral homeotic functions. The expression patterns of the cDNAs corresponding to different homeotic classes was analysed in 18 wheat tissues and floral organs by RT-PCR, real time RT-PCR and northern hybridisation. Potential functions of the genes corresponding to the cloned wheat cDNAs were predicted on the basis of sequence homology and comparable expression pattern with functionally characterized MADS-box genes from Arabidopsis and monocot species.